Add short code store, bot commands (/start, /status, /help), and
POST /telegram/connect-code endpoint for Desktop to create QR codes.
Users scan a QR → Telegram opens → /start {code} → auto-connects.
- ShortCodeStore: in-memory Map with TTL for connection info
- Bot commands registered via setMyCommands
- Refactor handleConnectionLink into shared connectUser method
- Fetch bot username via getMe() for deep link URL
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
